Range finder



July 24, 1928.

G. GRIFFITH RANGE FINDER yFiled oct. 11, 192e NVENTOR n IIllllllllllIlllrlllllllll S. ,.,f/ N f, a .i lunmmmi: @wd :|11 11, -li

m 1 I Il @um Y H i ...ful .l Lw, ,A ,m S Q Q MN .Q `W QQ. b N\I.| Q /Lsi A TTU/elw Patented July 24, i928.

UNITED STATES PATENT OFFICE.

GRAVES GRIFFITH, OF SAN FRANCISCO, CALIFORNIA.

RANGE FINDER.

Application filed October 11, 1926. Serial No. 140,863.

" tance is determined, the principle involved being dependent upon thetrigonometrical solution of right-angled triangles.

rlhe principal object of the present invention is the provision oi:- asimplied form ot the variable-base type of instrument in which reliancetor image coincidence is based uponV movements through are of a pair oipri-smat-ic telescopes, rather than to` the movements of either areflective or a retractive element along the path of a reflected ray asin present practice, and the recordationot1 these arc-movements asmeasures of distance by means of the rotation ot' a circularscale-member co-operatively associated in movement with those of theprismatic telescopes. f

Supplementary to the preceding is that of providing a simple andeiiicient` precision instrument for determining distances adaptable foruse by surveyors, engineers, and military and naval oiiicers.

Other objects and advantages will appear as this specificationprogresses and be more fully set iorthin the claims hereto ap-l pended.Y

In the accompanying drawings, forming a part of the specilication and inwhich similar characters of reference refer to like parts, throughout:

Figure 1 is a rear view in elevation, with a part broken away, showingthe reartelescope in perpendicular position, the two telescopes inhorizontal extension, dotted lines, representing the eXtreme limitl otbase for a particular instrument, the circularl scale member andgraduations, the prism for scale illumination, the scale indicator asborne by the emergent tace of this prism, members ot the commonactuating mechanism controlling the movements of the two telescopes andscale member, the casing bearing the telescopic and scale members, andthe mounting adapting the instrument to field use;

Figure 2 is a vertical section, side elevation, showing the twotelescopes in perpendiculaiposition and horizontal alignment androtatively connected, the character and arrangement of the opticalsystems ot' the two telescopic members, the scale member and its meansof illumination, the common mechanism for the synchronized actuation ofboth telescopic members and scale member,

lthe ocular, the tripod head, and the manner of mountingthe instrumentupon the tripod head, where intended iior ield use;

Figure 3 is a plan view ot the image plane, i

showing the two portions of the iield, the one inscribed within the.other', and the displaced sections of an image as they would appearbeiore being brought into coincidence; and y Figure 4e is a.diagrammatic view illustrative o'` the diterent planes of operation, thetriangulation principle involved for the varying bases, and the circularsweep in opposed directions otthe telescopicv members required to bringdisplaced images intocoincidence. y

Referring to the drawings with greater particularity as to details, 1indicates in a general way the head, of usual transitcon# struction,bearing the yoke 2 in which the housing 3 is revolubly supportedv bytrunnion-s 4 and t, ai'ter the manner of that oi' the telescope of theordinary transit. y The optical systems consist of two telescopicmembers 5 and 5 ot' prismatic character, each comprising an initialray-receiving reiiective element 6, 6, an objective 7, 7 ocusable by ameans j', f, a linal reflective ocular element 8. 8, and an ocular 9common to both said telescopic members.

The telescopic members 5 and 5 are rotatably connected, as indicated at10, by means of sleeves 11 and 11 borne respectively by these membersand adapted to aii'ord a means ot intercommunication therebetween and oisuch arrangement as toperinit partial rotationabout the incident ray 12finally rc fiected by the element S" as an axis of rotation, thisrotation being eliected through the gears 18 and 13 borne respectivelyby these members and actuated by the mechanism 14;, the telescopicmembers being further rotatively supported in bearings 15 and 15 borneby the housing 3. f

vThe reflective elements constituting the reloo flective systems of thetelescopic members, as indicated, are of like character but oppositedisposition, this disposition resulting in the reflective action of therhomboidal pri-sm, in which, when rotated about a fixed axis, the imagesare caused to follow arcuate courses while retaining their erectpositions.

rlhe rearmost 8 of the ocular reflective elements has a central section8y of its hypotenusal reflective prism surface 16 removed, or renderedlight transmissive, to permit the light rays reflected centrally b'y theelement 8 to pass unobstructed therethrough to the image plane.

lt may 'be pertinent in this connection to note that, in theconstruction of the element 8, the central reflective surfacere1noved,'or rendered light transmissive, vis preferably of circularform, and that', as applied to prisms, it may be recessed, or it may'beprovided for exteriorly of the hypothenusal surface and cementedthereto, only observing that its entrant face be in parallelism with theemergent! face of the prism clement.

The scale member for registering the degree of movement of thetelescopic members necessary to bring about image coincidence consistsof a transparent circular member 17 borne by the shaft 24l and bearingmarginally graduations 19, the scale member occupying a position in thein'iage plane and being adaptable for rotation therewithin, there beingalso provided for the illumination of its graduations a. prism means 20-bearing upon the face 21 a scale indicating means 22.

The operating mechanism 14C rcomprises the divided shaft 211%24, carriedrespectively in rbearings 25, 25 and 25 and 26 and 26', and bearingrespectively bevel-gear 27 and 27 lmeshing 'with the bevel-gear 28 borneby the shaft 2,9 carried in bearings 30, the shaft 29 being additionallyprovided with a knurled knob 31 'for its actuation. The shafts 24: and24 respectively are further provided with gears 33 and 33 in mesh withthe gears 13 and 13 carried by the telescopic members 5 and 5 and servefor the rotation through arc of these members, the proportion betweenlthese gears being such that a movement through quadrant for each of themembers cause a complete revolution of the scale member 17, carried alsoby this shaft 24.

The image field, as it would appear for displaced images, is shown inFigure 3, the image `heilig' represented by `a flag and its staff g thecentral field 34 bearing the middle portion ,of the staff displaced tothe right, while the circumscribing portion of the field 34 bears theflag and remaining portions of the staff displaced to the left. As is tobe observed, there are here presented double the usual number ofcontactingpoints for coincidences, conditions insuring greater certaintyand vprecision in this direction.

The principles of triangulation involved are presented diagrammaticallyin Figure 4l. Here A A represents the base line of an instrument; e. e'a. line bisecting the base line at a and at right angles thereto; Z), c,l and z' distance points along the line c e', this line constituting theline of direction; a a the vertical position of thetelescepic members 5and 5'; a 7i, 7L g g e and e A, arc movements described by thetelescopic member 5 in bringing the points I), c, d and i into propercoincidence position; ci 7i', 7L g, g e and e A, arc movements described.by the telescopic member 5', similar to those described by the member 5and for a like purpose; 71, L, g g, e c and A A, lines para/lleling eachother and the equivalents, respectively, of the chords of the sums ofthe preceding arcs taken in couplets of similary equal arcs; A A z', c ed, g g c and '7L L .5, similar isosce'les triangles, and a v72 a g, a eand c A, and a 7L', a g, c c a A", the different positions assumed,respectively, by the telescopic members 5 and 5 in (.lescribing thesearc movements. It is obvious that, if a plane peririendicular yto A Awere passed along c i, it would bisect those riangles. producing uponeither side of the plane an equal number of similarright angledtriangies whose variable bases would be proportionate to theirrespective other sides, thereby aflilording the required data fordistance measurements.

The scale graduations for an instrument of a particular base limit arearrived at by directing the instrument upon an object at a known orcalculated distance, ybringing about coincidence of images, andascertaining the proportion between the variable base thus secured andthe known distance, and graduating the scale accordingly. No 4provisionsare made for obtaining the distances to very near objects, as theblanking of the rear by the forward telescopic member prevents-a mattei'of no particular consequence.

In operation, the instrument with its telescopic members in verticalposition is levelled and directed upon the object whose distance isdesired and the image .as presented through. the forward telescopicmember brought to the center of the image field. Vith the instrumentclamped in this position, the telescopic members 5 and 5 are rotated inopposed directions, through the medium of the knurled knob 31, until theimages are brought into coincidence, when the reading for distance istaken directly from the scale 17 as indicated by the means 22.

The instrument as here presented isadapted more particularly to fieldwork, and may, in addition to distance finding, be `applied to that ofthe transit or theodolite by simply retaining the telescopic members inthe vertical position, as both altitude and azimuth Cil movements areprovided tor in connection with the usual compass.

Having thus described my invention, I claim, and desire to secure byLetters Patent: v

l. A light reflective element ot prism torni having centrally kandexterioi'ly ot its reflective Jface and cemented thereto a lighttransii'iissi e cylindrical eienient fashioned to conform to said taceand having its entrant tace in parallelism with that ot the emergentita-ce ot said prism a reflective prism element in co-operativeassociation with said' cylindrical element and having the axis ofrellection of its reflective surface in co-axial alignment with the axisoiC said cylindrical element, and a tubular connecting means olublyuniting said prism elements and adapted to permit their rotation inopposite directions through quadrant and about said co-axis as the oirotation.

2. In an instrument ot the character dcscribed, the combination with anocular, ot a pair ot reflective systems each compr d of an upper andlower oppositcly dispoed prism element, the upper elements ot the twosystems constituting the initial ray-receiving and reflecting featuresand the lower elements oi2 the two systems the ocular reflectingfeatures, the rearward of said lower elements being rendered centrallylight transmissive and the Jorward of said lower elements being adaptedto direct light centrally to and through said light transinissivesection ot said rearward lower element, the two systems being similar,and parallel and means whereby the two systems may be rotated inopposite directions on a common axis passing through the axis otreflection ot' the two lower reflective elements.

3. ln an instrument ot the class described, the combination with anocular, ot a pair ot co-opcratively associated prismatic telescopes,means for mounting the telescopes l'or rotation. in opposite directionsthrough quadrant about a common axis, said axis being in alignment withthe optical axis oit the ocular.

il. ln an instrument ot the character described. the con'ibination withan ocular, ot a pair cl co-operatively associated prisinatic telescopesmeans whereby the telescopes may be rotated in opposite directionsthrough quadrant and about a common axis said axis being in alignmentwith the optical axis ot said ocular, a circular scale memberco-operatively associated with said telescopes tor registering thedegree oirotation imparted to said telescopes, and a common means ytorthe actuation in synchronisn'i ot both said telescopes and said scalemember.

5. In an instrument ot the character -described, the combination with anocular, of a pair ot co-operatively associated prismatic 1 registeringthe degree of rotation imparted to said telescopes, a common means torthe actuation in synchronism of both said telescopes aiid said scalemember, a means tor scale illumination, and an indicating means arrangedto indicate scale movement.

6. ln a distance determining instrument, the combination with an ocular,of a pair ot' similar co-operatively associated prismatic telescopesadapted for rotation through quadrant in parallel planesl and oppositedirections about a common axis in co-axial alignment with that ot theoptical axis of said ocular, the said telescopes being coniprised,respectively, ot spaced and oppositely disposed reflective prismelements and an objective, the upper of said prisms constituting theinitial ray-receiving elements and the lower the ocular prism elements,the rearmost ot said ocular prism elements being rendered centrallylight transmissive to permit the passage freely therethrough of thelight reflected centrally by the forward of said ocular prism elements,a transparent scale member bearing graduations intermediate said ocularand the rearmost of said ocular prism elements, and a common means torthe rot-ation in synclironism of the said scale member and the saidtelescopes about the said common axis.

7. ln combination, a pair' ot similar prismatic telescopes positioned inparallel planes and rotatably united tor coi-operative association neartheir lower extremities by a tubular connection, the said telescopescomprising each a reliective system constituted ot two similar, spacedand oppositely disposed prism elements in cooperatively associatedalignment with an objective, the lower element of the rearwardreflective system being rendered light transmissive centrally torthepassage therethrough of light as retlected centrally by the lowerelementof the forward reflective system, the said tubular connection beingarranged and adapted 'for the passage therethrough of the light as thusreflected, as well as an axis ot' rotation tor said telescopes, atransparent circular scale member adapted to register rotative movementsot said telescopes, a common mechanism adapted for the rotation insynchronism oit said telescopes in opposed directions through quadrantand said scale member through a complete revolution, a means for themarginal illumination of said scale' member, a scale indicator carriedby said means, and means tor the magnification and observation of theimage ield as presented b y and through the said telescopes and alsothat or the scale graduations as illuminated by said scale illuminatingmeans.

8. The combination, in an instrument of the character described, of abase mount bearingy yokes, a housing' supported in said yokes bytrunnions and adapted for vrotation in a vertical plane, an ocular bornerearwardly by said housing, a pair of similar prisniatic telescopicmembers feo-opera# tively associated with said ocular through the mediumolf their lower prism elements, said prism elements being in eo-aXialalignment with the optical axis ol" said ocular and said telescopicmembers adapted for rotation `thereabout through quadrant, means borneby said members lor their vac- -mation, a mechanism ope 1ativelyconnected With said means, a revoluble circular transparent scale memberco-operatively associated with said mechanism and adapted to registerthe degree of movement oi' said telescopie members, a means for theactuation of said mechanism, and an illan'iinating means and anindicating' means for said scale.

In testimony whereof I hereunto alii); mr l signature.

y GRAVES Gl'lFFITH.

